Exercise may preserve motor skills in seniors

By Kathryn Doyle

(Reuters Health) - Being physically active may offset some of the effects of brain aging on seniors' motor skills, according to a new study.

In the most active participants, the number of white matter hyperintensities, a specific sign of brain aging, did not predict a person's motor abilities, researchers found.

This may partly explain why older people who are more active tend to have better motor function, the authors write article published online March 11 in Neurology.

"The association between physical activity and motor function in older adults is well established," said lead author Debra A. Fleischman of Rush University Medical Center in Chicago. "What is less understood is the biological basis of that association."

Higher numbers of white matter hyperintensities (WMH) have been linked to movement difficulties.

In the new research, the researchers used data from an ongoing study of aging, focusing on 167 people 60 to 96 years old without dementia. All wore activity monitors for up to 11 days.

They also underwent MRI brain imaging and 11 motor performance tests, measuring grip strength, pinch strength, finger tapping as well as tests of lower body function.

Based on their own reports, the study participants were physically active for an average of four hours per week.

People with more white matter hyperintensities on MRI tended to have poorer motor function, and those who were more active each day tended to have better motor function, but total daily activity was not related to the number of brain spots, the authors write.

With statistical modeling, as activity level increased, the number of white matter hyperintensities became less important for predicting motor function.

For participants in the 90th percentile of daily activity, who walked an extra 90 minutes each day, researchers found no association between hyperintensities and motor function. But for those at the 50th percentile, they found an association - more hyperintensities, poorer function.

"What was notable was that WMHs had no effect on motor function for the persons at the highest percentile of physical activity, whereas they did affect motor function for those at the 50th percentile and the effect was even stronger for the persons at the 10th percentile of activity," Fleischman told Reuters Health by email.

Exercise did not seem to protect against these spots, but did appear to somehow circumvent their effect on motor function. But this study only looked at people at one point in time, so it does not indicate that one factor, like exercise, caused another factor, like better motor function, she noted.

Still, the findings held when she and her coauthors accounted for other possible influences like weight, depressive symptoms, vascular disease, functional status, and pulmonary function.

"To determine whether physical activity is causally related to improved mobility would require a randomized study," according to Dr. Richard Camicioli of the University of Alberta in Edmonton, Canada, and Joe Verghese of Albert Einstein College of Medicine in New York City.

In an editorial, they say it's difficult to tell from this study which aspects of daily activity might have been protective. The nature of physical activity, its complexity, and frequency may all be important.

"I think that the important message, and the one that I give to my patients, is that they do not have to be marathon runners to maintain cognitive and motor function through physical activity as they age," Fleischman said.

SOURCE: http://bit.ly/18z6I8i and http://bit.ly/18z6JJ7

Neurol 2015.

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